<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  
  <script>

    function average(a){
      let sum=0
      let aver
      let flag=true;
      let arr2=[]
      for(let i=0;i<a.length;i++){
        if(a[i]%2!==0){
          sum+=a[i]
          arr2.push(a[i])
          flag=false
        }
      }
      aver=sum/arr2.length
      if (flag) {
        return 0
      } else{
        return aver
      }
    }

    let arr=[2,9,8,11,10]
    console.log(average(arr));
  </script>
</body>
</html>